Article Figures & Data
Figures
- FIG 1.
Right base of tongue SCCa (p16 +) with bilateral nodal metastasis with high uptake on initial PET/CT (A) and near-complete treatment response on the follow-up study (B). The ct-DNA results (C) show concordant values with a pretreatment value of 2357 and negative (< 2) results on surveillance with a quantitative value of zero. A mild increase in ct-DNA values is noted on the initial treatment test (2531) secondary to tumor necrosis.
- FIG 2.
Discordance between imaging and ct-DNA results. Surveillance PET/CT (A) in a patient with treated p16+ oropharyngeal SCCa shows a nodular focus with increased FDG uptake in the left tonsillar fossa (black arrow), concerning for tumor recurrence. Multiple surveillance ct-DNA tests (B) during the same period, however, showed negative values, and the consensus during the multidisciplinary tumor board was against any intervention. Follow-up PET/CT (not shown) revealed complete resolution of uptake with findings consistent with posttreatment changes.
- FIG 3.
Recurrence of p16+ oropharyngeal SCCa along the left lateral neck with concordant imaging and ct-DNA results. Surveillance contrast-enhanced neck CT (A) and PET/CT (B) in a patient with treated p16+ oropharyngeal SCCa show nodular enhancement with increased FDG uptake in the left lateral neck (black arrows), concerning for tumor recurrence. A marked increase in values from 0 to 544 was seen on the concurrent ct-DNA test. This increase was treated with surgical resection (curative intent) with a return of ct-DNA values to zero (negative) on follow-up surveillance.
Tables
Results with absolute number and percentages of positive and negative imaging findings and CT and/or FDG-PET/CT (total cohort = 34 patients)
Total Cohort (n = 34) 100% ct-DNA CT FDG-PET/CT Long-Term Surveillance or Pathology Outcome Concordant negative 22 (64.7%) 22 (Negative) 22 (Negative) Negative on long-term surveillance Discordant 8 (23.5%) 7 of 8: Negative ct-DNA results and positive findings on imaging Negative on long-term surveillance 1 of 8: Positive ct-DNA results and negative imaging Positive on pathology Concordant positive 4 (11.7%) 4 (Positive) 4 (Positive) Positive on pathology Note:—NPV = 100%, PPV = 100%.
